In machines for preparing coffee and infusions in general that work with capsules, piercing devices are known which are adapted to pierce a capsule that contains substances of various kinds in order to make hot water, cold water, a liquid, a fluid, a beverage and the like filter through said capsule, so as to obtain the desired infusion.
The piercing operation is therefore very important, since the holes for the inflow of the hot water and the exit holes of the infusion are formed during such operation.
More particularly, known types of piercing devices generally comprise an upper plate and a lower plate, which face each other and are provided, on their mutually facing faces, with wedges adapted to pierce the capsule.
For obtaining the infusion, the capsule is interposed between the two plates, which are subsequently moved, producing the relative approach of the two plates, by moving one or both.
In any case, with this movement the wedges of the two plates penetrate the capsule, piercing it and providing the entry and exit holes described earlier.
In order to optimize and speed up the infusion process, the wedges of the two plates define in their interior part of the channels for the passage of the hot water and of the infusion.
More precisely, the hot water, which arrives from an appropriately provided injection device, flows within the wedges of the upper plate and is injected into the capsule through adapted openings provided in the part of the wedge that has penetrated said capsule.
Likewise, the infusion generated by the filtration of hot water through the substances contained in the capsule is discharged through the wedges of the lower plate by means of adapted openings provided in the part of the wedge that has penetrated the pod and is discharged into an adapted discharge device, which is connected to an infusion collection element.
These known types of piercing devices are not devoid of drawbacks, which include the fact that the wedges with which the upper and lower plates are provided are not always able to penetrate the capsule correctly, causing fraying and/or penetrations and therefore producing unwanted leaks of water and/or infusion.
In order to obviate this drawback, it is known to provide the wedges with flat fins that form cutting edges adapted to facilitate the penetration of the wedges into the capsule, allowing the correct operation of the machine.
Nonetheless, with known types of piercing devices, even if they are provided with wedges that have flat cutting fins, the risk of piercing the capsule incorrectly, causing the leaks cited above, is high.